OldButNotDead wrote:If you have good electrical tracking skills this may not be as hard as it may seem. If not, I recommend finding someone who has those skills to help. Spider or no spider you can check the ground circuits in that controller back to the frame or battery ground. Check continuity and resistance. Once you determine that it is a ground problem, then you will have to track the harness to the spider or whatever they are using as the common grounding point.
Something that might be a "too easy" is to check if there is socket connector for that controller and if so check to see if it has come loose.
Just took a look at the wiring diagram. Two potential culprits IMO would be a socket marked 70 which is the connector for the left handlebar switch. Another is marked as 30 and is defined as Coupler 3 which is probably a spider. That Coupler 3 is where the the common ground is, I think. Not 100% sure, too lazy to track all the lines. Nice thing about these schematics is that it isn't obvious where these things are physically located. Good luck.
Sorry,but I disagree on checking ground with continuity or resistance (opposites of the same test). Its a faulty measurement by design of the instrument. Grounds should be checked from the suspect component to the MOST negative point in the system (read: negative battery terminal) using a volt meter. Anything above about .1 V in a 12 V system is suspect. This should be done with the system "live".
We can discuss theory etc. as to why, but after troubleshooting thousands of ground problems on about anything running DC, I can say checking voltage drop will save time and confusion.
So, to diagnose this:
1) get the electrical diagram out
2) find every malfunctioning component
3) look for their common connection. A copy of the diagram and some highlighters are very helpful in complex situations.
4) check the common component or junction THOROUGHLY. Do more than clean it and think its OK. Do proper voltage drop tests.
Its usually not easy. Ground problems are extremely confusing...until you find the problem, then it all makrs sense. However, its also not a multiplex communication bus, so you have that going for you.
One notable instance covered is the operation of the wind screen while in the on but not running condition. So, look for something denying the windscreen ground in the running condition. This may be a component that, while OFF is providing a ground, but not while in operation. Eliminating that false ground will help find the true ground issue. In the mechanic's lingo, it was called " back feeding" which is not technical, but the best term I have known to describe it. It is a bear to diagnose.
If necessary, I'd be willing to help over the phone, but understand its like trying to give someone a haircut over the phone...